The invention relates to the field of flags and other display devices; more particularly, it relates to a wind accessory for a tethered display device.
Flags and display banners of some type have probably flown, unchanged, for over 5000 years. The conventional flag and banner design has two serious flaws: at low wind velocities, the flag or banner hangs limp or flutters listlessly around its pole; at higher wind velocities, the flag pops and snaps disagreeably, and frays and tatters the end of the flag, promoting relatively short useful life.
So far as I am aware, no one has ever adequately addressed either of these two problems. While there exist a variety of flag hanging apparati, and numerous approaches to dealing with flag drape and tangle problems, there has been no solution proposed for the problems identified above.
What is needed is an improved flag or banner device that, when tethered to an appropriate pole or other anchor, catches or makes use of low velocity wind to fly the device out fully and majestically, while it also stands up to higher velocity winds without snapping or fraying. For low wind conditions, or conditions where there is no natural wind, what is also needed is an air delivery system that automatically directs air from a supplemental wind generator to the banner or tethered display device until a sufficiently strong natural wind blows again.
Accordingly, it is an object of the invention to provide an improved flag or display banner device that, when tethered to an appropriate pole or other anchor, catches or makes use of low velocity wind to fly the device out fully and majestically.
It is a further object of the invention to provide an air delivery system that, when connected between the flag pole and the banner, directs a generated wind to the banner to fly the device out fully and majestically in an absence or insufficiency of natural wind.
It is another object of the invention to provide an automatic means of switching between a xe2x80x9cnaturalxe2x80x9d wind when available and a generated wind when xe2x80x9cnaturalxe2x80x9d wind is not available, or not sufficient to xe2x80x9cflyxe2x80x9d the device.
It is a further object of the invention to provide an improved flag or display banner device that, when tethered to an appropriate pole or other anchor, flies in higher velocity winds without snapping or appreciable fraying.
It is another object of the invention to provide a tethered display device, such as a flag or banner, that makes use of a tubular channel integral to the device and made of vertical panels and top and bottom seams that catches and directs low velocity wind to fly the device.
It is another object of the invention to provide a tethered display device, such as a flag or banner, that makes use of a relatively soft airfoil in a tubular channel, both integral to the device that provides lift to the device so that it flies in low winds.
It is yet another object of the invention to meet any or all of the needs summarized above.
These and such other objects of the invention as will become evident from the disclosure below are met by the invention disclosed herein.
The invention addresses and provides such a system. The invention represents the first tethered flag or display device that will fly in very low winds, or, with optional windpole, no wind at all.
Application of the invention to the needs expressed above is especially beneficial in that the invention is the only system that effectively provides both low wind flyability and high wind stability.
The invention provides in one embodiment a tethered display device with at least two vertical panels connected at a top seam and a bottom seam. The panels are preferably cloth or other soft and flexible material. The panels and seams define at least one tubular channel through which air can flow. The two panels can simply be sewn at top and bottom edges to create the channel, or optionally the panels can be connected, such as by sewing, by a top panel and a bottom panel of some suitable width. Because the vertical panels, and top and bottom panels if any, are soft, the device can still xe2x80x9cflutterxe2x80x9d in a breeze. Preferred devices will take care that they do not therefore become xe2x80x9cengorgedxe2x80x9d with wind (like a conventional windsock), and so eliminate or undermine their ability to so flutter. One way to avoid such engorgement is to fashion the devices without appreciable taper, or other like end attenuation, so as not to xe2x80x9ctrapxe2x80x9d the wind.
In preferred embodiments there are multiple channels in each device. Preferred embodiments will also have at least one soft airfoil horizontally disposed between, and connected to, the two vertical panels. In the simplest airfoil embodiment, the airfoil defines two tubular channels, the one above the airfoil and the one below it; in each airfoil embodiment, an airfoil so defines in part at least one of the tubular channels.
One embodiment has a soft wing-like airfoil that is curved so that a mid portion of the airfoil is closer to the top of the device than are the end portions of the airfoil. A flow of air across and beneath the airfoil thus produces an aerodynamic lift on the airfoil.
In some embodiments there are multiple airfoils. The multiple airfoils can take the form of a single layer of multiple horizontal airfoils, arrayed more or less in xe2x80x9cwavesxe2x80x9d from opening to outlet of the device. In other embodiments, a plurality of horizontally disposed airfoils may be vertically stacked (like a biplane""s wings) with respect to each other.
In some embodiments, an airfoil is otherwise unsupported and is air filled (like a sail), and may optionally and advantageously have a permanent xe2x80x98attack anglexe2x80x99 xe2x80x98sewn inxe2x80x99 or otherwise fixed. In other embodiments, there are airfoil fasteners at one or both edges of the airfoil, and the fasteners connect the airfoil to the vertical panels so that the airfoil shape is determined by its fasteners, regardless of whether the foil is xe2x80x98filledxe2x80x99 or not. This fixation and connection helps spread out the lift imparted to the device and prevents an xe2x80x98end lift onlyxe2x80x99 phenomenon, which can cause undue bending of the foil itself and so cause collapse of the foil and loss of lift.
The airfoil may be directly fastened to the vertical panels such as by sewing or stitching, or by use of grommets or the like, as will be appreciated by those skilled in the art. Alternatively, the airfoil may be indirectly fastened so that the airfoil has at least one edge connected to a vertical panel by a plurality of strings, threads, or other soft connectors as will occur to those skilled in the art, each string having differential lengths cut in advance to suit the filled shape of the foil.
Optionally, the vertical panels themselves are cut with a fullness that allows them to serve as foils themselves so as to provide a xe2x80x98liftxe2x80x99 effect normal to the panels, thus to spread the panels and to laterally tension the horizontally disposed airfoils. This may be necessary in specialty higher wind applications, where high velocities through the channels tend to so reduce channel internal pressure, so that the panels might otherwise tend to collapse inwardly on themselves and the airfoil(s). In such embodiments, the horizontal airfoils may be cut so they are full (filled) only when the vertical panels are full (filled).
In such specialty applications, lateral stiffeners may alternatively be employed to hold the vertical panels apart to prevent vertical panel inward collapse at higher internal air velocities.
The display invention may advantageously and optionally be employed in combinations with some kind of artificially enhanced windsource, such as a funneling device for directing ambient wind into or onto the display device. Optionally, the windsource may be artificially induced, such as by the windpole invention described herein.
The invention also provides a windpole comprising a vertical hollow pole, at least one duct, and at least one port. This windpole may be used as a tether for the display device of the invention and in combination with it. It can be passive, or in little or no wind situations, it can provide enough xe2x80x9cwindxe2x80x9d itself to fly the display device of the invention. The windpole invention preferably includes a fan, and in some embodiments the hollow pole is itself the duct. The pole has a plurality of in line ports to vent the wind from the pole onto or into the wind channels of the device.
The invention may also provide a separate duct inside the pole that runs roughly parallel with the axis of the pole, with the fan mounted for moving air along the duct, as from a relatively bottom located intake duct, and the pole may advantageously employ a plurality of ports connected by subducts to the main duct.
Where the hollow pole is itself the duct, a plurality of in line ports in the pole may each have an associated scoop to direct airflow to its port. Optionally these scoops may increase in cross sectional area progressively from a bottom scoop to a top scoop. The pole itself may also be internally tapered from bottom to top.
As an embodiment alternative to the vertical internal duct in the pole discussed above, a plurality of roughly horizontally disposed cross ducts in the pole may be employed, with each cross duct having its own fan at one end, and each cross duct ending in one of the ports. The cross ducts may either be tubular, or the ducts may be open horizontally disposed chambers in the pole, so that with an optional rotatably mounted port sleeve having a plurality of in line exhaust ports, each such port roughly aligned with a chamber, and a like plurality of intake ports, each intake port more or less aligned with a corresponding exhaust port and with a particular chamber, the display device when tethered to the port sleeve will act like a wind vane to rotate the intake and exhaust ports into line with the prevailing wind, while the chamber fans draw air through the intake and expel it from the exhaust port into and onto the device. This option is therefore adaptable to provide an air velocity boost to ambient or prevailing air motion, no matter what direction it comes from.
The pole invention may optionally and advantageously have a conventional wind sensor and a fan controller receiving a control signal from the wind sensor so that fan powered air can be attenuated or eliminated as ambient air velocities reach a level sufficient to fly the device without assistance.
The invention provides in one embodiment a wind accessory device to allow the tethered display device or banner to be lifted at all times regardless of the force of natural wind present. The invention comprises a director having air intake ports for both natural wind and generated wind, output ports to the flying banner or display device, an automatic wind source switching mechanism, a means of attachment to a flagpole and a banner, a wind source, and in some embodiments an internal light source.
The invention further optionally has variable internal stiffeners xe2x80x9csleevesxe2x80x9d, whereby rigidity of the director may be varied. The invention preferably attaches between the flagpole and the banner, and by a variety of means, though the banner and wind director can advantageously be integral to one another. The air intake port for generated wind preferably has an integral modular connector for air inlet from the wind generator. In an alternate embodiment the fan could be placed inside the invention, either in or under the modular connector. A further variation of the invention is to employ a wand or handle beneath and supporting the modular connector so that the invention can be carried by hand, or the handle can be inserted into a weighted base in conventional fashion, or inserted into a base having a battery or AC line power supply. Alternatively, the batteries may be disposed in the handle.
The invention advantageously uses an automatic wind source switching mechanism to allow natural wind to be used when available and select generated wind when natural wind is not available or sufficient. The generated air is directed into the banner through the output ports and is blocked from escaping the natural wind intake ports. When generated wind is shut off, preferably by a controlling wind sensor, natural wind is free to enter the intake ports and pass through to the output ports. In one embodiment flaps are used to do the blocking of the natural wind intake ports. In a preferred embodiment a blocker is turned by the force of generated air passing through a turbine or other vaned wheel mounted in the generated airstream, to which the blocker is rotatably connected. Alternatively generated wind goes through the turbine, the force through its vanes causes it to rotate and lift the blocker with a conventional eccentric or cam to a closed position. When there is no generated wind the turbine is conventionally spring biased to an open position and the blocker falls back and opens the ports. As a further alternative, the turbine wheel is threadably connected to a central shaft so that as the turbine is driven around by the generated wind, it rises up the central shaft and thus pushes up a blocker in riding engagement upon the turbine wheel, or simple turns a blocker mounted on a section of the periphery of the wheel into a blocking position. In either case, because the wheel is free to fall down the shaft when the generated wind is stopped, the blocker is gravity biased into the open position (that is, so positioned that the natural wind port is open). In such embodiments, the generated wind is of sufficient force to effect the movement of the blocker, while still providing enough airflow to the banner to fly it.
The invention optionally allows a banner or tethered display device to be lighted from a light source inside the director, such as a neon or incandescent light.
In an alternate embodiment the invention uses an air supply tube connected to a wind source that runs along a flagpole. The tube is flexible so it can be coiled up in the base of the flag pole. Adjacent the banner, the tube has multiple outlets along the section adjacent to the banner and the outlets face the banner, and direct air to it.
Yet another alternate embodiment of the invention is a method of flying a display device, the method having the step of directing an airflow into a tubular channel in the device, and toward at least one horizontally disposed curved soft winglike airfoil in the device to impart an aerodynamic lift to the airfoil.